1. Technical Field
The present patent application relates to portable power sources and, in particular, relates to a portable power source operable to selectively provide power to a device connected to an interface of the portable power source.
2. Description of the Related Art
Portable electronic devices, such as Portable Digital Assistants and media players, typically include one or more rechargeable batteries housed permanently (or somewhat permanently) within the portable electronic device. These portable electronic devices sometimes also have peripheral bus ports that are able to support peripheral buses, such as Universal Serial Bus (USB) or FIREWIRE (IEEE 1394) bus ports. Peripheral buses are used to provide data communications with electronic devices as well as to provide limited amounts of power to the electronic devices. The power typically originates from a host computer to which the electronic device is connected via the peripheral bus.
In some situations, it can be impossible, or very inconvenient, to recharge the internally-housed batteries of a portable electronic device. This is typically due to lack of access to a suitable source of power. For example, many airliners do not have available a source of power suitable to recharge batteries of portable electronic devices.
On the other hand, external batteries (e.g., disposable AA batteries) can be somewhat easily obtained and carried to operate a portable electronic device in situations where the internally-housed rechargeable batteries are discharged and a source of recharge power is not conveniently available. However, configuring a portable electronic device to accommodate the use of both external batteries and internally-housed rechargeable batteries can be detrimental to the portability of the device.
Thus, there is a desire to accommodate the use of external batteries with portable electronic devices, while minimizing the detrimental effect to the portability of the electronic devices.